1. Field of the Invention
This invention relates to a method of and apparatus for removing meat from the bone of edible animals, especially edible avian animals, and more particularly, to a method of and an apparatus suitable for removing meat from the thigh bone.
2. Description of the Prior Art
Heretofore, the breeding, slaughtering and carcass processing of edible avian animals have been done with equipment which has become extremely large in scale, and various operations have become automated. However, the operation of removing tight means from bones separated from the carcass is still mostly carried out manually, thereby requiring a great deal of man-hours.
Further, in the operation of removing thigh meat from a bone obtained from a domestic fowl leg by cutting the bone off at the femoral joint and cutting off an end portion of the spur, a skilled operator can process an average of 720 thighs (i.e., 360 fowls) per day. In addition, since the operation is carried out by touching the edible meat with the hands, a high overhead cost is required with regard to maintaining edible meat sanitation.
To obviate such drawbacks, a proposed method of automatically removing thigh meat from the bone is disclosed in Dutch Patent Application No. 8,700,213. Briefly, this method uses a film member, which is made of polyurethane or similar tenacious elastic material and has a circular opening with a diameter slightly smaller than the average diameter of the bone of a fowl leg. On the back side of the circular opening a receiving section is provided to receive meat with bone. Meat with bone is pushed from the back side of the receiving section with a piston, while the bone part is pulled out from the circular opening. The pulled-out bone part is clamped with a clamp, and the work is pushed with the piston and pulled-out with the clamp concurrently to remove the bone.
In this method, however, during the bone removal the meat is crushed, and it is impossible to obtain meat having a neat shape.
One of the reasons for this is the pushing of the work with the piston. As the meat is pushed by the piston, it is squeezed as it is stripped off.
A second reason is that since the bone workpiece is passed directly through the stripper comprising the elastic film member, smooth bone removal can not be achieved if the meat is strongly attached to the bone. Particularly, the leg muscle of a fowl is attached to the bone via the tendons at the end of the upper and lower thigh side on the opposite side of the knee joint, and therefore the meat connected to the tendons is pulled apart during the bone removal, resulting in residual meat remaining on the bone without being stripped off.
Further, since the stripper is a film member, it deteriorates rapidly with continued use.
To obviate the above drawbacks, the applicant has proposed a method, in which a belt-like cutter wound on one end of the meat-carrying bone is brought into between the meat and bone in order to remove the meat from the bone, as disclosed in Published Japanese Patent Application No. S59-21337.
With this method, however, the belt can not be moved along the bone surface but enters the bone, or it can not satisfactorily clear the ligament in the joint, but intrudes into the ligament or the cartilage.
Techniques for preventing the intrusion noted above by using a belt-like cutter having an outwardly arcuate sectional profile. This structure, however, results in residual meat remaining on the bone without being stripped off.
In either of the above cases, with the method of bone removal with the sole belt cutter it is difficult to obtain smooth bone removal and it also takes a long time to complete the bone removal because of the presence of the tendons in the vicinity of the joint.